Phonographic apparatus



Aug; 23, 1949. w. K. RIEBER PHONOGRAPHIC APPARATUS 3 Sheets-Sheet 2 Filed Oct. 12, 1945 'INVEN TOR.

Aug. 213, 1949. w. K. RIEBER 2,479,640

PHONOGRAPHIC APPARATUS Filed Oct. 12, 1945 3-Sheets-Sheet 3 INVENTOR. I

Patented Aug. 23, 1949 UNITED STATES PATENT OFFICE PHONOGRAPHIC APPARATUS William K. Rieber, Los Angeles, Calif.

Application October 12, 1945, Serial No. 622,062

8 Claims.

My invention pertains to the subject matter of my copending application, Serial No. 603,961, filed July 9, 1945, entitled Sound translating device, and relates generally to phonographic recording of the type whereby a sound record is produced in the form of an undulating spiral groove in the surface of a disc record.

My invention relates more particularly to a method of controlling the speed of the record supporting turntables of sound records, wherein the spiral sound record groove is engraved or embossed by a vibrating stylus in the surface of a disc-shaped record.

It will be seen that the spiral path of the record groove is the product of two modes of motion, 1. e., rotary motion of the turntable and translatory motion of the stylus thereon. Obviously the translatory motion can be achieved either by moving the stylus mounting means or by moving the turntable in translation while it rotates. Both these methods are old in the art.

Frequently, the same mechanism used to make a record is subsequently used to play-back or transcribe said record. It is of considerable convenience and advantage, therefore, to provide controls for such phonograph apparatus that enable it to be quickly and easily converted from the function of recording to the function of transcribing. It is of further advantage to employ the same stylus for embossing the groove during the recording process and for following the embossed groove to reproduce sound therefrom during the transcription process. In such dual purpose apparatus the stylus is mounted in an electro-mechanical transducer, which serves either to convert electrical pulsations into mechanical vibrations of the stylus, or conversely to convert mechanical vibrations of the stylus into electrical pulsations. Such transducers are Well known in the art and need not be described here.

Duringthe recording process it is necessary to apply considerable downward pressure to the stylus in order to force it into the recording medium. and enable it to emboss or engrave a groove therein. During the subsequent transcription of the record most of this pressure must be removed since it would result in injury to the sound record and distortion in the reproduced sound. Thus, it will be seen that one of the principal changes in the apparatus necessary to convert it from recording to transcribing consists in removing a large proportion of the pressure on the stylus.

The introduction of this pressure during recording, however, has the additional and un-' ing play-back. The result of this differential drag,

is that the tangential velocity of the groove is different during recording than it' is during transcribing since during recording some slippage in the friction drive may occur and the shaded pole motor, if such is used, may be slowed somewhat.

Attempts have been made to correct this difl'iculty by introducing an extra drag on the turntable during transcription. All such methods have, however, introduced this drag as a constant countertorquethat is, the drag has been ap plied to the turntable at one effective radial distance only, regardless of the operational position of the stylus. It will be seen that such a practice falls short of correcting the difiiculty since the slowing effect of the recording stylus becomes less and less as the stylus moves inwardly on the record. Therefore, any drag which is introduced to correct the speed during transcribing should be applied to the turntable always at the same radial distance as that at which the stylus drag was applied during recording.

Stated differently, since the drag of the recording stylus produces a constantly changing countertorque, therefore, any extraneous drag introduced to correct the speed during transcribing must also produce a constantly changing countertorque of the same value and changing at the same rate as the stylus drag torque.

It is one object of my invention to provide a phonographic transcriber in which the speed of play-back is corrected to correspond exactly to the recording speed at all times.

It is another object of my invention to provide a dual purpose phonographic recorder-transcriber in which conversion of the device from one function to the other automatically actuates a turntable speed correcting means.

These and other objects will appear from the following disclosure.

In a preferred embodiment of my invention, I have adapted the device for use in a constant tangential velocity type of recorder-transcriber, which employs frictionally driven turntable, and is designed to serve either as a recorder or as a transcriber. In the constant tangential velocity type of apparatus the point of frictional engagement of a drive wheel with the turntable is constantly changed during the progress of recording or'transcribing in such a manner that the effective radius at which the turntable is driven is at stant drag and hence non-varying countertorque 1 applied to the turntable, it is impossible to correct the play-back speed within the allowable percentage variation mentioned namely, 2%. By the application of my invention, however, I found it possible to correct the play-back speed of a constant tangential velocity recording and play-back apparatus to within less than 1% difference from the recording speed at all parts of the record. l

For more detailed descriptions of two embodiments of my invention, reference should now be had to the attached drawings in which: v

Fig. 1 is a plan view of a constant tangential velocity phonographic apparatus embodying my invention, with the turntable removed to show underlying parts.

Fig. 2 is a front elevational view of the device shown in Fig. l with the turntable in place and a record disc placed thereon.

Fig. 3 is an isometric view of .a portionof the device shownin Fig. 1 including the tone head and associated controls which parts are in position for recording.

Fig. 4 is an isometric viewof the portion shown in Fig. 3 but with the parts in position for playing-back.

Fig. 5 is an isometric view of the portion shown in Fig. 3 but with the parts in-a neutral, nonoperating position.

- Fig. 6 is a plan view of a constant radial velocity phonographic apparatus employing my invention. The turntable has been removed to show underlying parts. 7 f

Fig. 7 is an elevational, sectioned, partial View of the apparatus shown in Fig. 6, taken on the line 1-4 in Fig. 6.

Fig. 8 is a front elevational view partially sectioned, taken on the line 8-8 in Fig. 6 with the apparatus in one of two operational positions.

Fig. 9 is a front elevational view of the apparatus shown in Fig. 8, but in the other of the two operational positions.

Fig. 10 is a partial isometric view of a friction brake and operating means employed in the apparatus shown in Fig. 6.

Figures 1 through 5 inclusive show a preferred embodiment wherein a flat rectangular shaped casting 28 forms a base. Integrally cast with the base and projecting upwardly therefrom are supports for the various parts of the apparatus. The recorder-transcriber is of the constant tangential velocity type, in which a turntable 2|, serving as a support for a record disc 22, rotates and moves in translation simultaneously. The.

turntable 2! is mounted to the upper end of a spindle 23 for rotary motion therewith and car-- ried in two horizontal bearing blocks 24 and 25,

disposed one above the other and secured between two vertical plates 23 and 29. The upper block 24 has a journal bearing 26 mounted therein and the lower bearing block has a combination journal and thrust bearing 21 mounted therein.

The vertical plates 28 and 29 have journal bearings 30, so spaced and aligned as to receive a cylindrical lead nut 3|, the nut being secured between the plates and adapted for rotary motion therein about its own axis. The rearward portion of each vertical plate has a horizontal slot adapted to pass over a horizontal track rod 32, which is mounted parallel to the base 20 by means f two upwardly projecting pillars 33 and 34 cast integrally with the base. 7

Passing through the lead nut 3-! and threadily engaged therewith is a rotatable lead screw 35 journally and pivotally mounted in two upwardly tioning of the turntable 2|.

projecting pillars 36 and 31 cast integrally with the'base. At the left end of the lead screw 35, as viewed in Fig. 2, is a crank 38 for manual rotation of the lead screw and hence, manual posi- Concentric with and centrally located on the lead nut 3| is an outwardly projecting worm gear portion 39 of such dimension as to engage a worm portion 40 of the spindle 23. Thus, it will be seen that the two horizontal blOcks Y24 and 25/ the two vertical plates .23 and 2.9, and the lead nut 3| form a carriage 19, which supports the turntable and spindle.

When the lead screw is fixed against rotation by means of a set screw 4i located at its left end near the crank, as viewed in Fig. 2 rotation of the lead nut 3! about the lead screw will cause the carriage unit 19 and the turntable 21 to move in translation along the lead screw, the rear portion of it being slidably supported by the track rod 32. ,As .a consequence Of this arrangement, when the turntable 2| is rotated, such rotation results in its simultaneous translation. Thus, a fixed stylus .42 engaged with the surface of the record 22 traces a spiral track thereim-the pitch of the spiral being determined by the pitch of the threads on the lead screw 35 and the gear reduction achieved through the worm portion and the worm gear 39.. In the case of my present embodiment, the pitch is 216 grooves per inch. I have found by experiment that when employing such groove spacing, undulations of the spiral groove embossed in the record of such magnitude to adequately record sound are not of a sufficient magnitude to encroach on adjacent grooves.

The stylus 42 serves either to embcss a spiral groove in the record surface during the process of recording or to reproduce sound from an already recorded groove. These two functions are performed by means of an electro-mechanical transducer 43 which is mounted to the outer end of a horizontal arm 44, which arm is pivotally supported at its rearward endfor vertically swinging motion about a pivot pin 45. The support for the pivot 45 of this arm is provided by an upwardly projecting, bifurcated pillar 45 cast integrally with the base 20.

Electrical leads 41 are provided by which the transducer 43 may be connected to the output of an amplifierdurin the recording process and to the input of an amplifier during the play-back process. Means for selectively making these connections are well known in the art and need not be described here.

As has been stated, it is necessary to apply considerable downward pressure to the stylus 42 during the recording process, and in the instant embodiment this pressure is produced by means of a weight 4.8, which may rest on top of the transducer 43. The weight is further supported by a rearwardly projecting arm 49, which is pivoted about the pivot 45 and is adapted for vertical swinging motion above said transducer. Mounted to the front of the weight 48 is a downwardly projecting hook-shaped member 50, which is adapted to engage a forwardly projectin boss 5! on the front of the transducer 43, thereby to lift the transducer and stylus 4201f the surface of the record 22 when the weight 48 is lifted to its uppermost position, as best seen in Fig. 5. Sufiicient play is permitted between the hook 50 and the boss 5| so that the weight 48 may be partially lifted to a position best seen in Fig. 4 without disturbing the transducer 43. Thus, it will be seen that there are two operative positions and one inoperative position of the weight 48.

The three positions are best seen in Figs. 3, 4, and 5, wherein it will be seen that in the recording position (Fig. 3) the weight 48 rests on top of the transducer 43, thus pressing the stylus 42 into the record 22. In the play-back position (Fig. 4) the weight has been lifted from the transducer 43 allowing it to engage an already recorded groove with reduced vertical pressure; and in the inoperative position (Fig. 5) the weight has been lifted to a posiiton where the hook 50 engages the boss 5| and lifts the stylus 42 from the surface of the record.

A control shaft 52 with a rectangular cam 53 mounted thereon for rotary motion therewith is provided for the purpose of lifting or lowering the weight into any of the three above mentioned positions. The cam engages a cam follower 54, which projects outwardly to the right from the weight 48, as best seen in Fig. 3.

Mounted to the forward end of said control i shaft 52 is a handle 55 for manual rotation of the shaft and the cam 53. It will be seen by an examination of Figs. 3, 4, and 5, that when the control handle is in a right-hand horizontal position (Fig. 3), the weight 48 is in the recording position. When the handle is in a vertical position (Fig. 5), the weight 48 is in the inoperative position, and when the handle is in the left horizontal position (Fig. 4), the weight is in the playback position.

The rotary motion of the turntable 2| is produoed by driving it with a drive wheel 56 frictionally engaged against its under surface. The drive wheel is fixedly mounted to the left end of a shaft 51 for rotation therewith, and is driven at a constant velocity by a shaded pole motor 58, which is belted to a flywheel 59 fixedly mounted to the right end of the shaft 5?, as best seen in Fig. 1.

In order to adjust the play-back speed to be identical with the recording speed a friction drag is applied to the fly-wheel during the play-back process. Friction drag is produced by a brakeshoe 65, which is cemented to the forward end of a resilient leaf 45!. The leaf is fixedly mounted to an articulate L shaped member 62, which is pivoted at its rearward end for horizontally swinging motion about an upwardly projecting pillar 65 cast integrall with base 20. The motion of the member 52 is such as to enable swinging of the brake-shoe into contact with the flywheel, or away therefrom.

Pivotally mounted to the forward en of the L shaped member 52 is a connecting rod 63 which projects to the left and engages a round eccentric cam 54 keyed to the control shaft 52 for rotation therewith. The cam and connecting rod function to move the brake-shoe 60 into engagement with the flywheel 59 during the play-back process and to release the brake-shoe from the flywheel during the recording process. Figs. 3 and 4 show the shoe 60 in these two positions and it will be seen that the position of the lobe of the eccentric cam 64 is opposite to the position of the control handle 55.

The apparatus illustrated is operatedas follows: A record disc 22 is placed on the turntable 2i and while the control handle is in the inoperative position (Fig. 5), the turntable is manually adjusted by means of the crank 38 to its extr-eme right hand position as indicated in Fig. 1 by the numeral [8. The set screw 4| having been loosened to enable rotation of the lead screw, is now tightened and power is applied to the motor 58, thus starting the rotation of the turntable. The control handle 55 is now turned to its right hand horizontal position, thus lowering the transducer 43, its stylus 42, and the weight 46 into the recording position.

The directions of the worm gearing 39 and and the threads on the leadscrew 35 are such that as recording proceeds, the turntable 2| moves in translation towards its left hand limiting position indicated by the numeral l! in Fig. 1. During the recording process the transducer is connected electrically to the output of an amplifier.

When the desired amount of material has been recorded, or when the turntable has reached its extreme left hand position [1, the transducer 43 and its stylus 42 are lifted by turning the control handle to its vertical position and the motor is stopped. It will be noted that during this recording process the brake-shoe has not engaged the flywheel -59.

Now, to play-back this recording, the set screw 45 is loosened and the turntable is manually returned to its extreme right hand position I8, the clamp screw retightened, the motor started, and the control handle turned to its left hand horizontal position. This will lower the transducer, permitting the stylus to engage the groove, but the weight will not rest on the transducer. It will also be noted that in this play-back position the brake-shoe E0 is now engaged with the flywheel 59 consequently introducing a countertorque. By proper proportioning of the resilient leaf 5| this countertorque can be made to exactly equal the countertorque of the stylus during the recording process. The play-back process may now continue in a similar manner to recording, to the end of the recorded groove.

i A second and less preferred'embodiment of my invention is shown in Figures 6 through 10, inclusive. The phonographic apparatus illustrated is of the constant radial velocity type. All parts of the second embodiment, which are identical to those in the first, are indicated by similar numerals primed.

The constant'radial velocity recorder differs from the constant tangential velocity type in that the turntable is driven directly by a motor 58' mounted to the front of the spindle carrying carriage 59', as best seen in Figures 6 and 7. Since the turntable is directly driven and hence there is no variation in speed reduction in the second embodiment, the variable countertorque is achieved by applying a friction drag to the under surface of the turnable and at a point directly under the point of stylus engagement. Friction drag is produced by a brake-shoe 60' and resilient leaf Bl mounted to the left end of a lever 10 which is in turn secured to a shaft H for swinging motion therewith. The brake-shoe-carrying shaft H is journally mounted parallel to and immediately below the; control sha-itil and the two shafts are linked together by means of a E i", connecting rod: t2, and. lever arm 13.. The cam fit is: secured to the control. shaft 52' and the lever arm is secured to the brake-shoe-carrying shaft so that operational rotation oi the control: shaft 52" operates either to engagethe brakeshoe with the under surface of the turntable, as shown in Figure 9, or to disengage it, as: shown in Figure 8. As previously described,- Figure 8 shows the transducer, weight, and stylus in a. recording position and Figure 9 shows these partsin aplayback position; The operation of the second embodiment is identicai to that of the first, the variation in the oountertor ue being produced by the rectilinear motion of the turntable. and the consequent change in: the efliective radius at which the iriction drive is applied. i

While I have shown only two methods of embodying my inveniton in phonographic: apparatusvarious others will become apparent to those skilled the art. For instance, the countertor ue drag may be applied to the motor or the: periphery oi the drive wheel. As another means:

for accomplishing the objects of my invention,

the friction drag could be applied at a fixed eiiec-- tive radius but the frictional engagement pressure varied. during the progress of the record to produce the varying countertorque.

: The countertorque produced during recording is a moment which is the product of the resistance of the recording stylus times the effective radial distance from the center of the turntable at this force isapplied. The corrective countertorque applied during play-back is a moment which is equal to the product of the drag force: oi the friction brake times the effective radistance at which it operates. It is the essence of my invention that this latter corrective moment be equal at all times to the recording stylus: moment at any corresponding instant during'record-ing I do not mean to be limited to the embodiments shown herein but rather to the scope of the appended claims.

I claim:

1. In phonographic apparatus for recording sound in a moving record medium and subsequently playing, back such sound record, the combination of: record. driving means; a stylus adapted to engage said moving record medium either for the purpose of recording sound therein or reproducing sound therefrom; reversable transducer means which when responsive to electrical pulsations vibrates said stylus, and when responsive to vibrations of said stylus produces electrical pulsations; means to selectively apply pressure to said stylus thereby to press it into said moving record medium for the purpose of making an undulating sound record therein, or to thereafter release said pressure and enable said stylus to faith-fully follow a sound record groove-formed in said moving record medium; and brake means connected to said pressure applying and releasingmeans for concurrent operation therewith to apply simultaneously with the release of said pressure, a friction drag to said record driving means.

2. In phonographic apparatus for recording sound in a moving record medium and subsequently playing back such sound record, the come bination of: record driving means; a stylus adapted to engage said moving record medium either for the purpose of recording sound there-- in or reproducing sound therefrom; reversible. transducer means which. when responsive to electricat pulsations vibrates said stylus, and when responsive to vibrations. of said stylus. produces electrical pulsations; means to selectively apply pressure to: said stylus thereby to press it. into said moving record medium for the purpose of making a. spirally progressing, undulating sound record groove therein, or to release said pressure and enable said stylus to faithfully follow a sound record groove: formed in said moving record medium; a brake connected to said pressure applying and releasing means for concurrent operation therewith to apply simultaneously with the release of said pressure, a friction drag to said record driving means, said friction drag being of such magnitude as to substantially compensate for the drag of the stylus when same is pressed into the record medium thereby to regulate the record speed to be constant during any function of the apparatus; and moment adjust-- ing means responsive to progress of said record groove for varying the magnitude of said friction drag.

3. A phonographic recorder-transcriber comprising in combination: astationary base struc ture; a, horizontal disc-shaped record carryingturntable; a friction wheel, j'ournally' mounted in said base structure, adapted to engage the under surface of said turntable thereby to rotate said turntable; a motor operatively connected to said friction wheel; a flywheel 0peratively connected to said friction. wheel; a carriage adapted to carry said turntable for simultaneous rotation and: rectilinear motion thereof With respect to said base structure; a lead member mounted in said base structure; a cooperative lead member journaled in said carriage structure operatlvely connected to said turntable so as to be rotated thereby, and engaged with said basev carried lea-d member so as when rotated to cause said rectilinear motion of said carriage and turntable; anelectro-mechanical, stylus carrying transducer adapted and mounted for vertical swinging motion above said turntable so that said stylus may selectively produce or follow a spiral track in a turntable-carried record; a. weight. mounted above said transducer; operable support means forsaid. weight such that said weight may be allowed. selectively, to rest on said transducer or be lifted therefrom; a friction brake mounted to said base structure and adapted to engage said flywheel; and connecting means between said weight support means and said brake such as to disengage said brake from said flywheel when said weight rests on said transducer and to engage said brake with said flywheel when. said weight is lifted.

4-. A. phonographic recorder-transcriber comprising. in combination: a stationary base structure; a. horizontal disc-shaped record-carrying turntable; a motor operatively connected to said turntable; a carriage adapted to carry said turntable and motor and such as to permit simultaneous rotation and rectilinear motion thereof. with respect to said base structure; a lead. member mounted in said base structure; a cooperative: lead, member journaled in said carriage structure operatively connected to said turntable so as to be rotated thereby, and: engaged with said. base carried lead member so as when rotated to cause said rectilinear motion of said carriage,

motor, and turntable; an electro-mechanical, stylus-carrying transducer adapted and mount.- ed for vertical swinging motion above said turntable so that said. stylus may selectively produce or follow a spiral track in. a. turntable carried record; a weight mounted above said transducer; operative support means for said weight such that said weight may be allowed, selectively, to rest on said transducer or to be lifted therefrom; a swinging and resiliently mounted friction brake mounted to said base structure and adapted to engage the under surface of said turntable at a point directly below said transducer carried stylus; and connecting means between said weight support means and said brake such as to disengage said brake from said turntable when said weight rests on said transducer and to engage said brake with said turntable when said Weight is lifted.

5. In a phonographic apparatus for recording sound in a moving record medium and subsequently playing back such sound record: record driving means; stylus and transducer means adapted to selectively engage said moving record medium either for the purpose of recording sound therein or reproducing sound therefrom; pressure adjusting means operatively associated with said stylus and transducer means and operable to apply pressure to press said stylus means into said record to make a sound track therein or to release said pressure to allow said stylus and transducer means to track a sound groove in said record; and brake means connected to said pressure adjusting means for concurrent operation therewith to apply simultaneously with the release of said pressure, a countertorque to said record driving means.

6. In phonographic apparatus for recording sound in a moving record medium and subsequently playing back such sound record: record driving means; stylus and transducer means adapted to selectively engage said moving record medium either for the purpose of recording sound therein or reproducing sound therefrom; pressure means operatvely associated with said stylus and transducer means adapted to apply pressure to the same for the purpose of producing a sound record groove in said record or to release said pressure for the purpose of playing back said record groove; and brake means connected to said pressure means for concurrent operation therewith to apply simultaneously with the release of said pressure, a countertorque to said record driving means.

7. In phonographic apparatus for recording sound in a moving record medium and subsequently playing back such sound record: means to support said record medium; record drive means engaged with said support means; stylus and transducer means adapted to selectively engage said moving record medium either for the purpose of recording sound therein or reproducing sound therefrom; pressure means operatiwely associated with said stylus and transducer means adapted to apply pressure to the same for the purpose of producing a sound record groove in said record or to release said pressure for the purpose of playing back said record groove; and brake means connected to said pressure means for concurrent operation therewith to apply simultaneously with the release of said pressure, a countertorque to said record driving means.

8. In phonographic apparatus wherewith sound is recorded by forming with a vibrating stylus an undulating spiral groove in a disc-shaped record and said sound record is subsequently played back by causing a stylus to track said undulating groove and including means for driving said record disc: selective transducer means adapted when in one condition to form said undulating sound groove in said record in response to electric vibration and when in another condition to produce electric vibration in response to undulation in said groove; means for adjusting the drive torque to correct the play-back speed of said sound record to substantially that of recording, said correcting means consisting in the combination of a brake which is adapted selectively to engage said driving means whereby to substitute, durin the play-back process, a friction drag for the recording stylus drag during the recording process; moment adjusting means for varying the effective radius at which said drive torque is applied to said record, whereby the moment which is a product of such friction drag and effective radius, is at any instant during the lay-back process equal to the moment which is a product of the recording stylus drag and its effective radius at a corresponding instant during the recording process; and linkage means connected between said transducer means and brake whereby said brake is applied when said transducer means are in said electric vibration producing condition and released when said transducer means are in said groove producing condition.

WILLIAM K. RIEBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 786,347 Darby Apr. 4, 1905 788,927 Miller May 2, 1905 1,253,276 Phillips Jan. 15, 1918 1,285,641 Dean Nov. 26, 1918 1,683,670 Hosoi Sept. 11, 192.8 2,069,136 Durand Jan. 26, 1937 2.307.475 Underhill Jan, 5, 1943 

